Plastic debris in lakes and reservoirs.

Plastic debris is thought to be widespread in freshwater ecosystems globally1. However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging2,3. Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 µm) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris4. Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services.

Multi-year renewal of green tides: 18 years of algal mat monitoring (2003-2020) on French coastline (Brittany region).

To better understand the green tide phenomenon impacting French coastline and give guidance to stakeholders to elaborate effective mitigation plan, an extensive survey has been deployed on Brittany hot spots. Based on 18 years monitoring database, the objectives of this work were to investigate the inter-and-intra annual evolutions of Ulva beaching, and to assess the parameters driving green tide annual renewal. The yearly cumulated area of Ulva mat on the Brittany coast averaged 2,42 ± 0,84 ha, of which 55 ± 12 % % was reported within Saint Brieuc-Binic Bay, with a maximal beaching generally observed in July. The renewal of green tide at spring time seems to be correlated with the Ulva bloom from the previous autumn period, particularly in bays with low exposure to swell. The residual stock, defined as Ulva fragments maintained in healthy conditions during the winter season, appears as highly dependent on nitrogen summer flows.

Anthropogenic Influences on Physico-Chemical Quality, Fish and Macrophyte Diversities of River Adofi, Southern Nigeria.

<b>Background and Objective:</b> Freshwater systems support agriculture, industry and even human existence. Pollution due to human activities affect the quality of water bodies thereby threatening biodiversity. This study, therefore, investigated the anthropogenic influences on physico-chemical quality, fish and macrophyte diversities of River Adofi. <b>Materials and Methods:</b> Three sampling stations along River Adofi at Ejeme-Aniogor (Station 1), Utagba-Uno (Station 2) and Umuleke-Ossissa (Station 3) were selected based on ecological features and the presence of human activities. Water samples were collected fortnightly for 6 months and water quality was determined. Fish and macrophyte species were collected and diversity indices were calculated. <b>Results:</b> Physico-chemical parameters were significantly different (p<0.05) in all three stations except for magnesium, calcium and nitrate. Temperature, total dissolved solids, conductivity, COD, total alkalinity and magnesium were higher (p<0.05) in Station 2 at Utagba-Uno where a rubber factory effluent discharges into the river. Out of 15 families, 18 genera and 26 species of fish collected <i>Oreochromis </i>species were more abundant, followed by <i>Gymnarchus niloticus</i>. Mokochidae and Clariidae had higher diversities than other families. Macrophytes recorded were 53 taxa from 21 families and 33 genera with emergent and submerged life forms dominating. Poaceae dominated with nine species. Shannon index increased with increasing species richness and evenness with both fish and macrophytes evenly distributed. <b>Conclusion:</b> Lower diversity of fish species observed in Station 2 may be due to influences of effluent discharges into the river while domestic and agricultural activities enhanced abundance and diversity of fish and macrophytes at Station 3.

Investigation of the presence of Legionella pneumophila in water samples from Erzurum and surrounding provinces in Turkey.

INTRODUCTION AND OBJECTIVE: Legionnaires' disease, which is a waterborne disease leading to pneumonia that can result in death, is one of the major health issues today. The study aims to carry out a three-year retrospective review of routine Legionella follow-up analyses in various samples taken mostly from hospitals in the province of Erzurum and nearby provinces, and to discover a the frequency of isolation of the agent and serogroups from each kind of media. MATERIAL AND METHODS: The study included a total of 2,025 water samples taken from hospitals, hotels, Turkish baths and shopping malls in Erzurum,and 13 nearby cities between 2016 and 2018. Samples were filtered by 0.45 µm-diameter membrane filter paper in the Public Health Laboratory of Erzurum and examined for L. pneumophila using culture method, according to the criteria set out in ISO 11731-2. RESULTS: The presence of L. pneumophila was found in 65 of the 2,025 water samples taken in hospitals, and in none of 40 samples taken in hotels, Turkish baths and shopping malls. L. pneumophila serogroup 2-14 was detected in 46 (70.8%) of 65 samples found positive, whereas L. pneumophila serogroup 1 was detected in 18 (27.7%). Furthermore, both the L. pneumophila serogroup 2-14 and L. pneumophila serogroup 1 were detected simultaneously in one example (1.5%). The first three samples indicate that the highest positivity rates were in hot water taps (11.6%), hot water tanks (6.1%) and shower heads (4.8%). CONCLUSIONS: The Prevalence rat of L. pneumophila was found to be quite low compared to other studies conducted in the western regions of Turkey. Legionella positivity was found to be higher in the hot water systems of hospitals and related points, compared to the other sample points.

Groundwater vulnerability assessment using GIS-based DRASTIC model in Nangasai River Basin, India with special emphasis on agricultural contamination.

Nangasai basin is a semi-arid watershed where agriculture is the main source of economy. In present day, increasing population demands increase in food productivity which leads to increase use of fertilizers and chemical pesticides in agriculture. These fertilizers on the other hand mix up with the groundwater and increase the pollution, which affects human health adversely. So, for controlling the groundwater contamination risk proper water resource management and assessment of groundwater vulnerability is extremely important. Total 7 hydrogeological parameters have been considered for this study, and the final groundwater vulnerability map has been prepared by overlay weighted method with the help of DRASTIC index, which is classified into 5 vulnerable classes (very high, high, moderate, low, and very low). In the south and south-eastern regions of the basin namely Deghi, Bankada, Baram, Macha, Katin, Tilabani high groundwater contamination is been observed. For validating the model, the water quality parameters-nitrate and TDS have been used with the accuracy of 89% and 86% respectively. Using effective as well as scientifically approved methods, the anthropogenic and agricultural contamination can be controlled and managed which will lower the risk of contamination. This map can be further utilized as a base map for management of groundwater pollution and its planning.

Water Sampling Module for Collecting and Concentrating Legionella pneumophila from Low-to-Medium Contaminated Environment.

The detection of water contamination with Legionella pneumophila is of critical importance to manufacturers of water processing equipment and public health entities dealing with water networks and distribution systems. Detection methods based on polymerase chain reaction or biosensor technologies require preconcentration steps to achieve attractive sensitivity levels. Preconcentration must also be included in protocols of automated collection of water samples by systems designed for quasi-continuous monitoring of remotely located water reservoirs for the presence of L. pneumophila. We designed and characterized a water sampling module for filtration and backwashing intended for analysis of low-to-medium contaminated water, typically with L. pneumophila bacteria not exceeding 50 colony-forming units per milliliter. The concentration factors of 10× and 21× were achieved with 0.22 and 0.45 µm filters, respectively, for samples of bacteria prepared in clean saline solutions. However, a 5× concentration factor was achieved with 0.45 µm filters for a heavily contaminated or turbid water typical of some industrial water samples.

Shifts in bacterial communities and antibiotic resistance genes in surface water and gut microbiota of guppies (Poecilia reticulata) in the upper Rio Uberabinha, Brazil.

Anthropogenic activities especially water pollution can affect the diversity and composition of microbial communities and promote the spread of antibiotic resistance genes (ARGs). In this study, water samples and guppies (Poecilia reticulata) were sampled from six sampling sites along the Uberabinha River in southeastern Brazil, both microbial communities and ARGs of surface waters and intestinal microbiota of guppies (Poecilia reticulata) were detected. According to the results of 16S rRNA amplicon sequencing, Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria were dominant phyla in both water and intestinal microbiota, but the abundance of putative pathogens was higher at heavily polluted sites. Up to 83% of bacteria in intestinal microbiota originated from water microbiota; this proportion was relatively higher in less polluted compared to polluted environments. ARGs providing resistance of tetracyclines and quinolones were dominant in both water and gut microbiota. The relative abundances of class I integrons and ARGs were as high as 1.74 × 10-1/16S rRNA copies and 3.61 × 10-1/16S rRNA copies, respectively, at heavily polluted sites. Correlation analysis suggests that integrons and bacteria play key roles in explaining the widespread occurrence of ARGs in the surface, but not in intestinal microbiota. We could rule out the class I integrons a potential intermediary bridge for ARGs between both types of microbiomes. Our results highlight the tight link in microbial communities and ARGs between ambient microbiota of stream ecosystems and intestinal microbiota of fish. Our study could have far-reaching consequences for fisheries and consumer safety and calls for investigations of gut microbiota of target species of both commercial fisheries and recreational (hobby) angling.

Large-scale pattern of resistance genes and bacterial community in the tap water along the middle and low reaches of the Yangtze River.

Antibiotic and metal resistance genes (ARGs and MRGs) in tap water are of great public health concern. However, very fewer studies focused on the relationship between resistance genes and opportunistic pathogens in tap water. In this study, the diversity and abundance of resistance genes and bacterial community from tap water at a large-scale along the middle and lower reaches of the Yangtze River were investigated. The total relative abundances of ARGs and MRGs were 2.95 × 10-3-1.22 × 10-1 and 1.93 × 10-3-1.20 × 10-1 copies/16S rRNA, respectively. The blaTEM and merP detected were major ARG and MRG subtypes, respectively. Mobile genetic elements (Intl1 and tnpA) showed significant correlations with the abundance of ARGs. Heavy metals also played a vital role in the co-selection of ARGs. Surprisingly, there were still eight opportunistic pathogens in tap water, among which Escherichia coli, Helicobacter pylori, Mycoplasma pneumoniae, and Porphyromonas gingivalis were the potential host of ARGs and MRGs. Escherichia coli had the highest abundance, while Bacillus anthracis had the highest detected frequency (100%), a widespread opportunistic pathogen in tap water.

A near-synoptic survey of ocean microplastic concentration along an around-the-world sailing race.

Litter and plastic pollution in the marine environment is of major concern when considering the health of ocean ecosystems, and have become an important focus of ocean research during recent years. There is still significant uncertainty surrounding the distribution and impact of marine plastic litter on ocean ecosystems, and in particular on the nano- and microplastic fractions that are difficult to observe and may be harmful to marine organisms. Current estimates of ocean plastic concentrations only account for a small fraction of the approximated 8 million tons of plastic litter entering the oceans on an annual basis. Here, we present the distribution of 100-500 µm microplastic particles within the ocean mixed layer, covering a significant fraction of the ocean, in a near-synoptic survey. During The Ocean Race 2017/2018 edition (formerly known as Volvo Ocean Race), two yachts served as ships of opportunity that regularly took samples of microplastics on a regular schedule during their circumnavigation. This effort resulted in information on microplastic distribution along the race track in the ocean's upper, well-mixed, layer. We found concentrations ranging from 0-349 particles per cubic meter, but with large spatial variability. There was a tendency toward higher concentrations off south-western Europe and in the southwest Pacific, and indications of long-range transport of microplastic with major ocean currents.

Predicting children's blood lead levels from exposure to school drinking water in Addis Ababa, Ethiopia.

Human beings could be exposed to impacts associated with heavy metals such as lead (Pb) through drinking water. The objective of this study was to evaluate quality of water consumed by kindergarten school children in Addis Ababa city, who are highly susceptible to issues related to heavy metals in water. Through conducting chemical analysis, using microwave plasma atomic emission spectrophotometry (MP-AES), the level of lead (Pb) was measured at 38 selected schools in the city. Drinking water samples were taken from three water supply sub-systems: Akaki, Legedadi, and Gefersa. Results revealed the average Pb concentration in the city was 62.37 µg/L which is significantly higher than the World Health Organization (WHO) recommended threshold value of 10 µg/L. The children's blood lead levels and exposure to Pb were also calculated using the integrated exposure uptake bio-kinetic (IEUBK) model as per USEPA guidelines. Estimated geometric mean blood lead levels (BLLs) for each school ranged from 4.4 to 13.2 µg/dL. On average, the model predicted that 20% of children in the city will have blood lead levels above the WHO recommended 10 µg/dL. The study can be considered as an unprecedented piece of work as it addresses critical issues and methods to mitigate problems caused by high concentration of Pb in water supply distribution infrastructure.

Comprehensive metagenomic insights into a unique mass gathering and bathing event reveals transient influence on a riverine ecosystem.

The religious mass gathering and bathing can pose a multitude of significant public health challenges and lead to severe alterations in the river microbial ecology. The Pandharpur Wari is an annual pilgrimage of Maharashtra, India, where millions of devotees carry the footprints of the saint-poets and pay their obeisance to Lord Vitthal on the 11th day of moon's waxing phase (Ashadi Ekadashi). As a part of the ritual, the engrossed devotees, walk over 250 km, take a first holy dip in a sacred river Indrayani at Alandi and secondly in Bhima River at Pandharpur. The MinION-based shotgun metagenomic approach was employed to examine the impact of spiritual mass bathing on environmental changes (concerning the river microbial community structure and functions); and public health aspects (in terms of changes in the pathogenic potential and antibiotic resistance). The analysis of bathing and post-bathing samples of both the rivers revealed alterations in the alpha and beta diversity, indicating significant spatiotemporal variations in the overall microbial structure and function. Furthermore, the analysis revealed up to 80% of differences in the abundance of virulence genes between the bathing and post bathing samples. We observed parallel increase of priority skin and enteric pathogens (ranging from 11% to 80%) such as Acinetobacter baumannii, Staphylococcus aureus, Streptococcus pyogenes, Mycobacterium tuberculosis, and Pseudomonas aeruginosa during the bathing event. Moreover, we observed a significant increase in the antibiotic resistance in the bathing samples of Bhima and Indrayani rivers respectively. Altogether, this is the first comprehensive metagenomic study unravelling the influence of religious mass-bathing on the riverine ecosystem.

Spatiotemporal Patterns in River Water Quality and Pollution Source Apportionment in the Arid Beichuan River Basin of Northwestern China Using Positive Matrix Factorization Receptor Modeling Techniques.

Deteriorating surface water quality has become an important environmental problem in China. In this study, river water quality was monitored in July (wet season) and October (dry season) 2019 at 26 sites, and a water quality index (WQI) and positive matrix factorization (PMF) model were used to assess surface water quality and identify pollution sources in the Beichuan River basin, Qinghai Province, China. The results showed that 53.85% and 76.92% of TN, 11.54% and 34.62% of TP, 65.38% and 76.92% of Fe, and 11.54% and 15.38% of Mn samples in the dry and wet seasons, respectively, exceeded the Chinese Government's Grade III standards for surface water quality. The spatial variation in water quality showed that it gradually deteriorated from upstream to downstream as a result of human activity. The temporal variation showed that water quality was poorer in the wet season than in the dry season because of the rainfall runoff effect. The PMF model outputs showed that the primary sources of pollution in the wet season were mineral weathering and organic pollution sources, domestic and industrial sewage, and agricultural and urban non-point pollution sources. However, in the dry season, the primary sources were mineral weathering and organic pollution sources, industrial sewage, and domestic sewage. Our results suggest that the point pollution sources (domestic and industrial sewage) should be more strictly controlled, as a priority, in order to prevent the continued deterioration in water quality.

A Probabilistic Approach to Evaluate the Risk of Decreased Total Triiodothyronine Hormone Levels following Chronic Exposure to PFOS and PFHxS via Contaminated Drinking Water.

BACKGROUND: Extensive exposure to per- and polyfluoroalkyl substances (PFAS) have been observed in many countries. Current deterministic frameworks for risk assessment lack the ability to predict the likelihood of effects and to assess uncertainty. When exposure exceeds tolerable intake levels, these shortcomings hamper risk management and communication. OBJECTIVE: The integrated probabilistic risk assessment (IPRA) combines dose-response and exposure data to estimate the likelihood of adverse effects. We evaluated the usefulness of the IPRA for risk characterization related to decreased levels of total triiodothyronine (T3) in humans following a real case of high exposure to PFAS via drinking water. METHODS: PFAS exposure was defined as serum levels from residents of a contaminated area in Ronneby, Sweden. Median levels were 270 ng/mL [perfluorooctane sulfonic acid (PFOS)] and 229 ng/mL [perfluorohexane sulfonic acid (PFHxS)] for individuals who resided in Ronneby 1 y before the exposure termination. This data was integrated with data from a subchronic toxicity study in monkeys exposed daily to PFOS. Benchmark dose modeling was employed to describe separate dose-effect relationship for males and females, and extrapolation factor distributions were used to estimate the corresponding human benchmark dose. The critical effect level was defined as a 10% decrease in total T3. RESULTS: The median probability of critical exposure, following a combined exposure to PFOS and PFHxS, was estimated to be [2.1% (90% CI: 0.4%-13.1%)]. Gender-based analysis showed that this risk was almost entirely distributed among women, namely [3.9% (90% CI: 0.8%-21.6%)]. DISCUSSION: The IPRA was compared with the traditional deterministic Margin of Exposure (MoE) approach. We conclude that probabilistic risk characterization represents an important step forward in the ability to adequately analyze group-specific health risks. Moreover, quantifying the sources of uncertainty is desirable, as it improves the awareness among stakeholders and will guide future efforts to improve accuracy. https://doi.org/10.1289/EHP6654.

Nontuberculous Mycobacterial Disease and Molybdenum in Colorado Watersheds.

Nontuberculous mycobacteria (NTM) are environmental bacteria that may cause chronic lung disease. Environmental factors that favor NTM growth likely increase the risk of NTM exposure within specific environments. We aimed to identify water-quality constituents (Al, As, Cd, Ca, Cu, Fe, Pb, Mg, Mn, Mo, Ni, K, Se, Na, Zn, and pH) associated with NTM disease across Colorado watersheds. We conducted a geospatial, ecological study, associating data from patients with NTM disease treated at National Jewish Health and water-quality data from the Water Quality Portal. Water-quality constituents associated with disease risk were identified using generalized linear models with Poisson-distributed discrete responses. We observed a highly robust association between molybdenum (Mo) in the source water and disease risk. For every 1- unit increase in the log concentration of molybdenum in the source water, disease risk increased by 17.0%. We also observed a statistically significant association between calcium (Ca) in the source water and disease risk. The risk of NTM varied by watershed and was associated with watershed-specific water-quality constituents. These findings may inform mitigation strategies to decrease the overall risk of exposure.

A Sediment Diagenesis Model of Seasonal Nitrate and Ammonium Flux Spatial Variation Contributing to Eutrophication at Taihu, China.

Algal blooms have thrived on the third-largest shallow lake in China, Taihu over the past decade. Due to the recycling of nutrients such as nitrate and ammonium, this problem has been difficult to eradicate. Sediment flux, a product of diagenesis, explains the recycling of nutrients. The objective was to simulate the seasonal spatial variations of nitrate and ammonium flux. In this paper, sediment diagenesis modeling was applied to Taihu with Environmental Fluid Dynamics Code (EFDC). Latin hypercube sampling was used to create an input file from twelve (12) nitrogen related parameters of sediment diagenesis and incorporated into the EFDC. The results were analyzed under four seasons: summer, autumn, winter, and spring. The concentration of NH4-N in the sediment-water column increased from 2.744903 to 22.38613 (g/m3). In summer, there was an accumulation of ammonium in the water column. In autumn and winter, the sediment was progressively oxidized. In spring, low-oxygen conditions intensify denitrification. This allows algal blooms to continue to thrive, creating a threat to water quality sustainability. The sediment diagenesis model, coupled with water quality measured data, showed an average relative error for Total Nitrogen (TN) of 38.137%, making the model suitable. Future studies should simulate phosphate flux and measure sediment fluxes on the lake.

Occurrence, trophic transfer, and health risk assessment of bisphenol analogues in seafood from the Persian Gulf.

The presence of chemicals in marine organisms is an important issue for human health due to the growing rate of seafood consumption. Potential exposure to seven bisphenol analogues through seafood consumption was investigated in some popular seafood from the Persian Gulf. Bisphenols were analyzed by gas chromatography-mass spectrometry. Bisphenol A (BPA) and bisphenol B (BPB) were the first and second most common bisphenols in the studied samples, respectively. The highest levels of BPA (mean 13.58 ± 5.70 µg/kg.dw) and BPB (mean 10.30 ± 7.98 µg/kg.dw) were found in E.coioides species. Bisphenol F and bisphenol AF were detected only in P. armatus and L. klunzingeri, respectively. Trophic transfer investigation demonstrated that BPA and BPB were biomagnified in the studied organisms through their diet. The eco-toxicity and estrogenic risk assessment indicated that seafood consumption does not pose a health threat to consumers. However, routine monitoring of bisphenols in seafood seems to be necessary to ensure food safety.

Concentrations of trace elements in the organs of commercially exploited crustaceans and cephalopods caught in the waters of Thoothukudi, South India.

Concentrations of trace elements (arsenic, cadmium, mercury, and lead) in tissues (muscle, gills, and digestive gland) of three commercially exploited crustaceans (Portunus sanguinolentus, Charybdis natator, and Penaeus semisulcatus) and three cephalopods (Doryteuthis sibogae, Sepia pharaonis, and Cistopus indicus) were examined. The animals were captured in the waters of Thoothukudi, and the tissues of six individuals of each species were analyzed using ICP-MS. The highest concentrations of arsenic (16.5 µg/g) and mercury (0.052 µg/g) were recorded in the digestive gland of C. natator, and cadmium (69.9 µg/g) and lead (0.351 µg/g) in the digestive gland of S. pharaonis. The edible portion of the crustaceans and cephalopods contained lower concentrations of trace elements, and these were below allowable limits set by the European Union. The edible parts of the investigated samples are safe for human consumption, but accidental contamination of the edible tissues with material from the digestive glands could lead to concerns relating to metal toxicity.

Sobol sensitivity approach for the appraisal of geomedical health risks associated with oral intake and dermal pathways of groundwater fluoride in a semi-arid region of south India.

The main objective of the present investigation is appraisal of human health hazard based on the intake and dermal contact of fluoride enriched potable groundwater used for rural water supply in a semi-arid region (Shanmuganadhi River basin) of south India. A variance decomposition based Sobol sensitivity method was used to assess the relative contribution as well as interaction of input variables for both oral and dermal models. Three different scores were evaluated: FOE (first order effect), SOE (second order effect) and TE (total effect) for different age groups of population including gender (kids, women and men). The spatio-temporal mapping indicates that about 26% of water supply wells exceeded the recommended limit (WHO) of fluoride (>1.5 mg l-1) for safe intake. These wells spread over 104.03 km2 area consisting 16 villages in the basin. To assess the human health risk related to fluoride enrichment in potable water, hazard index (HI) was calculated as per USEPA guidelines. The non-carcinogenic risk based on oral intake ranges from 0 to 1.81, from 0 to 1.59 and from 0 to 1.29 for kids, women and men respectively. Nearly 30%, 21% and 12% of well samples exceeded the upper permissible limit (HI > 1) for kids, women and men respectively. The Sobol sensitivity analysis reveals that, Cw (concentration of F- in water) and IR (intake rate) combination plays a vital role in the HQ oral model for the appraisal of health hazard in kids. However, these two parameters have negligible effect on health hazard for adult population (men and women). Therefore, lower age group people especially kids have significant ill effect due to the consumption of fluoride enriched potable water. The model output suggests that body weight (BW) has least effect on health hazard in the lower age group of population. Interestingly 'exposure frequency (EF)' and 'body weight (BW)' have not much effect on health hazards related to dermal contact, and 'skin surface area (SA)' has minimal effect for men (TE = 0.92) and women (TE = 1.26). However, 'SA' has vital effect for kids (TE = 17.39). Because of this, older age group people have more dermal risk than the younger people. Therefore, the HQ dermal results indicate that 49%, 64% and 67% of samples possess non-carcinogenic risk to the kids, women and men respectively.

Impact of fecal contamination on surface water quality in the São Francisco River hydrographic basin in Minas Gerais, Brazil.

Proper water quality monitoring is a valuable tool for water resource management, helping to identify polluting sources and risks related to the use of water resources. One of the main types of contamination found in Brazilian water bodies is fecal contamination, which originates mainly from point source pollution through wastewater disposal. Thus, this study analyzed water quality monitoring data from the responsible environmental body (Minas Gerais Institute of Water Management, IGAM), related to the fecal contamination indicator (FCI), for the years 2000-2018. This was done for the Minas Gerais portion of the São Francisco River basin (SFRB-MG), one of the most important basins in the country. The 10 sub-basins in the area were compared using statistical tools. The work found significant differences between the sub-basins in terms of FCI concentration, highlighting the most impacted ones (SF2, SF3, and SF5) as also being the most densely populated. It is necessary to invest in sanitation measures in order to ensure that water resources are preserved, as well as to reduce the public health risks of downstream municipalities that are supplied with previously contaminated water.